Japanese Stoneware: Born From Clay, Grown Through Use

Stoneware is pottery that comes out of the earth, and grows into itself through use.

The raw material is clay, fired at 1,100–1,250°C. At that temperature the body never fully vitrifies, so invisible pores stay inside it. That is why stoneware drinks water. Flick it with a finger and the note is low and stops dead; hold it to the light and nothing shows through. In the hand it feels a little thicker, a little warmer. What people call the earthiness of pottery is really those pores.

Material and firing are what set stoneware apart from porcelain

What separates stoneware from porcelain is the raw material, and that one difference changes almost everything about the finished piece.

How far does the word reach

In everyday Japanese, anything made of clay gets called touki. Strictly, though, there is a third category sitting between the two: sekki, fired at 1,200–1,300°C until the body tightens and stops passing water even without glaze.

Kilns that fire hot, like Shigaraki and Bizen, produce plenty of work that belongs in that middle category. So even among pieces sold as stoneware, how much water they take varies from one to the next.

• Yakishime　Fired hot with no glaze at all. Wood ash leaves the surface rough
• Shizen-yu　Wood ash settles on the pot and melts into a glaze inside the kiln

The great unglazed tradition is Bizen ware; the one that shows the grain of the clay itself is Shigaraki ware. The kilns running continuously since the medieval period are gathered in Japan's Six Ancient Kilns.

The craft of making clay white and beautiful

Clay carries iron, so it fires red-brown or grey. Laying white clay over the top is what turns it into a white, beautiful piece of stoneware.

• Shirogeshou　White slip over a red body, then glaze over that
• Kohiki　A kind of white slip. The clay bleeds through at rim and foot, and the piece changes with use
• Hakeme　White slip swept on with a brush, the marks left as the pattern

Porcelain is white from the start. The white of stoneware is slip and glaze colour. That is why the clay peeks out where the rim wears, and why the piece keeps changing. The glazes themselves are covered in Japanese pottery glazes.

Stoneware drinks water, and grows with it

What makes stoneware different to live with is that it absorbs water and grows. Water gets into the pores of the body, so colour stains in and character builds up.

Absorbing water does bring marks with it, but that is not only a bad thing. To keep the marks down, seal the pores with medome before first use, wash it right after use, and dry it properly instead of putting it straight back in the cupboard.

Related reading

Stoneware and porcelain

• Stoneware vs Porcelain: How to Tell Them Apart
• Earthenware, Stoneware, Porcelain: The Real Differences
• Japanese Porcelain: Made from Stone, Not Clay

Where stoneware is made

• Japan's Six Ancient Kilns: All 6 Regions Compared
• Shigaraki Ware: Why Its Clay Sparkles After 1,200 Years
• Bizen Ware: Pottery With No Glaze at All
• Kasama Ware: Japan's Most Free-Spirited Pottery Town

Laying white over clay

• Shirogeshou: How Japanese Potters Make Dark Clay White
• Yakishime: Unglazed Pottery Fired to Its Limit
• Shizen-yu: Natural Ash Glaze Explained

First use and care

• Japanese Stoneware Care: What Porcelain Never Needs
• Medome: How to Seal Unglazed Pottery Before First Use
• Pottery That 'Grows': How Ceramics Change With Use

Pieces available at Nokaze

• Japanese Plates | Handmade Ceramic Plates from Japan